Question

Find the total energy (ft-lb) of an aircraft weighing 20,000 lbs at 5,000 ft true altitude and 200 KTS true air speed. Group of answer choices

Answer 1

Answer:

Hello the options to your question is missing below are the options

2 x 10^8 ft-lb

15527950 ft-lb

2.8 x 10^7 ft-lb

13.55 x 10^7 ft-lb

Answer : 13.55 * 10^7 ft-Ib

Explanation:

Given data :

weight of Aircraft (p) = 20000 Ibs

height ( h ) = 5000 ft

Velocity = 200 KTS  = 370 km/h ( 10277 m/s) where 1 KTS = 1185 km/h

calculate the total energy

Total energy = potential energy + kinetic energy

potential energy = mgh = p * h =20000 * 5000 = 100 * 10^6 ft-Ibs

kinetic energy = 1/2 mv^2 = 1/2 * 625 * (33709)^2 = 3551 *10^6 ft-Ibs

where ; m = p/g = 20000 / 32 = 625 Ibs

             v = 10277 m/s ≈ 33709 ft/s

hence total energy = 100 * 10^6 + 3551 * 10^6 = 1355*10^7 ft-Ibs